Lap retruing machine



June 28, 1938. R. s. DUKE LAP RETRUING'MAGHINE Filed July 6, 1936 3Sheets-Sheet 2 Juhe 28, 1938. R, a DUKE 2,122,056

LAP RETRUING" MACHINE Filed July 6, 1936 3 Sheets-Sheet 3 Patented June28, 1938 UNITED STATES PATENT OFFICE This invention relates to a'lapre-truing machine.

It is an object of the invention to provide a machine of the characterdescribed and specially designed for reshaping the spherical or toricsurface of the lap, such. as are used in lens grinding and polishingmachines.

In the manufacture of lenses, such as optical lenses, a grinder isemployed, one element of m which comprises a lap having a grindingsurface which is of the curve of the desired surface of the lens to beground. As a result of use the active surface of the lap,be it eitherconvex or concave,

becomes misshapen from wear. It is an object of if this invention toprovide a re-truing machine wherein the grinding lap may be restored toitsoriginal curve or curves.

' It is another object of the invention to provide a machine of thecharacter described wherein the 20 misshapen lap may be mounted andwhich is equipped with an abrasivesurface arranged to .cooperatewith thelap and which is capable of the required adjustments to restore theactive surface of the lap to the original curve or curves, the

range of adjustment being such that a worn lap of any original sphericalor toric surface may be restored for further use in lens grinding andpolishing.

With the above and other objects in view, the 30 invention hasparticular relation to certain novel features of construction, operationand arrangement of parts, an example of which is given in thisspecification and illustrated in the accompanying drawings, wherein:

Figure 1 shows a side elevation of the lap retruing machine partly insection.

Figure 2 shows a cross sectional view of the stand taken on the line 22of Figure l.

Figure 3 shows a side view partly in section, 4 taken at right angles tothe view shown in Figure 1.

Figure 4 shows a'plan view. I

Figure 5 shows a cross sectional View taken on the line 55 of Figure 3.

Figure 6 shows a fragmentary side view partly in section, showing amodified form of the machine, and 1 I Figure 7 shows a fragmentarysectional view taken at right angles to the form shown in Fig- 50 ure 6.I a

Referring now more particularly to the drawings, wherein like numeralsof reference designate same parts in each of the figures, the numeral -ldesignates a suitable stand which is tubular in form and mounted on thebase 2. Fitted within the upper end of the stand there is a chuck 3which is splined therein against rotation by the key 4. The upper end ofthis chuck extends above the stand and is upwardly tapered and blank asat 5 to fit into the socket 6 of the lap 6a to be ground. The taperingportion of the chuck has a lateral key I which is received in the keyway8 of the shank of the lap whereby the lap is held against turning on thechuck. An intermediate portion 9 of the chuck is externally threaded andan adjusting nut I0 is threaded thereon andabuts the upper end of thestand whereby the chuck and the lap thereon may be vertically adjusted.

Vertically slidable on the support I there is a clamp I l which issplined thereon by the spline I2. The free ends of the clamp l'l havethe outwardly turned corresponding lugs l 3, l3. A clamp screw I4 isfitted through one of said lugs and has a threaded connection with theother and the outer end of this screw has the grips l5, whereby thescrew may be. turned to contract or expand the clamp ll. Laterallyoffset from, but rigidly secured to, said clamp there is the upstandingarm l6 and mounted on the upper end .of this arm to pivot on ahorizontal axis is the yoke IT. This yoke is mounted to pivot on thespindle l8 which is secured to the arm I6. One end of the yoke is formedinto the counterweight l9 and secured to the other end of the yokethereis a vertical guide 29. slidable on said guide and having adovetailed connection therewith there is a wrist bearing 2| in rightangular relation to the axis of the spindle [8.

A screw shaft 22 is mounted to swivel in a vertical bearing 23 at theupper end of the guide and this shaft 22 has a threaded connection withthe wrist bearing 2! whereby said bearing 2| may be adjusted vertically.The guide 20 carries a gauge 24 and the wrist bearing 2! is equippedwith a pointer 25 whereby the point of adjustment of the bearing 2| maybe approximately ascertained. For finer, or more accurate, adjustmentsthe upper end. of the bearing 23 is provided with a gauge 26 and theadjacent portion of the shaft 22 is provided with a mark 2'! to indicatethe adjustment of the shaft. The shaft 23 is equipped with a handle 28whereby it may be turned.

There is a crank arm 29 one end of which is formed into a wrist 30 whichworks in the bearing 2|. The other end of this arm is arranged oppositethe arm l6 and has a sleeve 3! provided to receive the lower end of theupstanding standard 32. The standard is secured in said sleeve by meansof suitable set screws 33. There is a file holder 34, one end of whichis formed with a vertical bearing 35, preferably square in crosssectional contour, and which is vertically slidable on the standard 32.The file holder may be secured at any point of adjustment on thestandard by means of the set screw 36 which has a threaded connectionwith the wall of the bearing 35 and whose inner end is adapted to bearagainst said standard. The outer end of the set screw 36 is equippedwith a g ip 3! whereby said set screw may be turned. The other end ofthe holder 34 is downwardly turned and provided with a lengthwise grooveforming a seat 38 wherein the file 39 may be seated and secured by setscrews 4|] threaded through the wall of said seat.

On the standard 32 thereis" argauger4l for indicating the radius of thedioptriccurvature of the operative surface of the lap 6a and the bearing35aha'sya :side window 42 which carries the transverse indicating line43.

When'the surface of the lapbecomes misshapen as aresult of use'it mayberemoved from the lens. grinding'machine and mounted on the chuck 3as-shown in Figures 1 and 3. Before mounting the lap in place; however,the screw. I4 is loosened and the clamp: I I elevated so as to move theholder 34 andifile'sSQ elevated out of theway, and the screw I4 maybethen tightened to cause the clamp I lgto. grip the stand I so as to'holdthe parts in elevated position. The lap 8a may then be-mounted in.place. 'The screw35 may then be released and the file holder 34 adjustedwith respect to the gauge 4Ito give the desired radius of :dioptriccurvature, that is, the base curve and the screw 36 then tightened up tosecurely fasten the file holder to the standard-32.

The wrist bearing H is now adjusted inaccordance-With the particularcontour desired for the toric surface of the lap. If said-last mentionedbearing be adjusted into a common horizontal plane with the bearing oftheyoke IT and the file 39 be operated over the surface of the lap andabout said bearings, as axes, a segment of a spherical surface will beproduced on the lap. If the wrist bearing 2! be adjusted'out of thehorizontal plane of the-yoke bearing the surface producedby thefile39-on the lap will be varied from atruespherical segment and willapproach a cylindrical surface, the variation in the particular form ofthe toric-suriace produced depending upon the relative adjustment of thetwo axes.

The screw I4 is then loosened and the clamp l I lowered until the filerests on the surface of the lap to be operated upon. The set screw I4 isthen tightened up to cause the clamp to grip the stand.

As'will be noted by-an inspection of Figures 1 and 3, a wide range ofadjustments has been provided for, to the end that any desired curvatureof the operative face of the lap 6a may be produced. During the progressof the work the nut III may be adjusted from time to time, to hold thelap closely to the work. When the lap has been ground to the desiredcontour'it may be removed from the chuck ready for use in" the lensgrinder or polisher.

As shown the'operative face of the-lap 6a is convex. This will produce aconcave face on the lensground thereon. If it be desired to produce aconvex face onthe lens, it is of course necessary'thatthe operative faceof the lap be concave as shown in Figure 6. v

As shown in Figures-6 and '7 the-holder 34a is I provided with a socket44 to receive the shank of the adjusting nut lUa. This nut is retainedin the holder by means of the transverse pins 45 which are fittedthrough the annular groove 46 around said shank. The chuck 3a isthreaded through the nut Illa. and the lower end of this chuck istapered as at a to fit in the socket of the lap 61). The taperingportion of the chuck Bot has a lateral key I which is received by thekeyway 8 of the shank of the lap 6b whereby said lap=is--held againstturningon the chuck. The

lap. Bbhas a concave operative face 41.

In this form there is a fork 48 having a spindle :48a which is keyed inthe upper end of the stand I, as shown in Figure 6, and mounted in thefork there is a-file, or other abrading member 39a. Thisfile39a is of ageneral cylindrical contour and it is provided with the end spindles 49which are'mounted' to rotate in the bearings formed in the .arms of thefork 48. These spindles are held against rotation by the set screws 53,5B. The surface of the abrading member 39a has the contour of aspherical segment and as the abrading surface becomes worn the member39a may be .partiallyt-turnedifrom time to time by loosening the setscrews 55!]. and upon making the adjustment again: tightening them up.

The weight [9 hereinabove referred to has been provided for'balancingthe adjusting and grind- .ing'mechanism, hereinabove described, aboutthe axis of the spindle I8.

" What I claim is:

13A: machine of the character described com- .prisingacstan'd a yokemounted onthe stand to pivot ona horizontal axis, a standard, means forsupporting the standard to pivot about a horizontal axis :onthe yoke,said supporting means being vertically adjustable, awork holder on thestand, a fileholder vertically. adjustable on the standard, .a file onthe file holder adapted to contact: the work, means for fixing thefileholder at any. point of adjustment on the standard.

20A machinefof the character described comprising a stand, a verticallyadjustable arm on ;the stand, means .for fixing the arm at any selectedpoint of adjustment, a yoke mounted to :pivot ona'horizontal axis on thearm, a vertically adjustable bearing on the yoke,-means'for adjustingsaid bearing relative to said axis,v a standard support having a wristmounted to pivot insaid bearing, an upstanding standard on saidsupport,a work holder on the standadapted toreceive and support the work to beoperated on, a file holder,: means for fixing the file holder at anyselected point of adjustment on the standard, :a "file on the holder incontact with the work.

'3.' Agrinding machine comprising astand, a yoke mountedon the stand topivot on a horizontal axis, astandard, means for supporting the standardto pivot about a horizontal axis on the yoke, said supporting meansbeing vertically adjustable, a work holder onthe stand, a file holdervertically-adjustable on the standard, a file on the file holder adaptedto contactthe work, means for fixing the file holder at any point ofadjustmento-n the standard-and means for adjusting the work on thestand.

4. A machine of the characterdescribed comprising a'stand', anarmadjustable longitudinally with respect to the stand, means for fixingthe armat anyselected point of adjustment, a'yoke 'mounted-topivot onthe arm on an axis at approximately right angles to the axis of thestand, a bearing on theyoke adjustable at approximately right angles to'the axis on which the yoke pivots, means for adjusting said bearingrelative to said last mentioned axis, a standard support having a wristmounted to pivot in said bearing, an upstanding standard on the support,a work holder on the stand adapted to receive and support the workto beoperated on, a file holder, means for fixing the file holder at anyselected point of adjustment on the standard and a file on the holder incontact with the work.

5. A lap re-truing machine comprising a stand, an arm adjustablelongitudinally with respect to the stand, means for securing the arm ata selected point of adjustment, a yoke mounted to pivot on the arm on anaxis at approximately 15 right angles to the axis of the stand, abearing on the yoke adjustable at approximately right angles to the axison which the yoke pivots, means for adjusting said bearing relative tosaid last mentioned axis, a standard support having a wrist mounted topivot in said bearing, an upstanding standard on said support, a workholder adapted to' receive and support the work to be operated on, afile holder and a file thereon, one of said holders being located on thestand and the other being located on the standard and' means for fixingone of said holders at a selected point of adjustment on its supportwith the file in contact with the work.

ROBERT S. DUKE.

